AEMO continues to work with ElectaNet, SA Power Networks (SAPN) and the South Australian Government to maintain the secure operation of the power system impacted by the fallen transmission tower on the Tailem Bend - South East 275 kilovolt (kV) transmission lines last Saturday (12 November).
South Australia’s disconnection from the NEM, as well as periods of low demand and high rooftop solar generation during spring, has required a range of actions to ensure a reliable and secure electricity supply while ElectraNet restores the transmission lines to service.
Tomorrow’s forecast weather conditions present the most challenging day since the transmission outage, with very high rooftop solar generation predicted.
AEMO, working with ElectraNet and SAPN, will continue to take the steps available to maintain system security since Saturday. This includes cancelling planned outages for transmission maintenance, increasing electricity demand by directing scheduled load into service or curtailing large-scale generation. The South Australian Government has also assisted by voluntarily curtailing its solar generation.
The curtailment of a proportion of commercial, industrial and residential rooftop solar generation has been undertaken by SA Power Networks continues to play an important role in managing the risk of widespread disruption in the event of a disturbance on the network.
These are, however, challenging operating times and as such AEMO will undertake further assessment tomorrow as conditions emerge to manage system security.
On Monday, AEMO determined that the rolling sum of the uncapped market ancillary ‘lower reg’ services price (a category of frequency control services) in South Australia exceeded the cumulative price threshold of $1,398,100 over the previous 2016 trading intervals.
Under the National Electricity Rules, AEMO applied an administered price cap of $300/MWh for all market ancillary services in South Australia until the end of the trading day (4am AEST). The administered price cap sets the market ancillary service price to $300/MWh if the uncapped ancillary service price exceeds $300/MWh in a trading interval.
AEMO will continue to monitor the rolling sum of the uncapped market ancillary service prices and issue further market notices as required. If the rolling sum of the uncapped market ancillary service prices exceeds the cumulative price threshold at the end of the trading day, then the administered price cap will be applied until the end of the next trading day.
A table of market ancillary service prices is available on the NEM Data Dashboard.
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